U.S. patent number 6,139,540 [Application Number 08/961,366] was granted by the patent office on 2000-10-31 for guidewire with disposition to coil.
This patent grant is currently assigned to Lake Region Manufacturing, Inc.. Invention is credited to Daniel L. Gabrielson, Michael C. Rost.
United States Patent |
6,139,540 |
Rost , et al. |
October 31, 2000 |
Guidewire with disposition to coil
Abstract
Guidewires having a substantially permanent disposition or
predispostion to assume the configuration of a coil are disclosed.
The guidewire assumes a coiled configuration when not in use and a
straight or substantially linear configuration when being used to
place a medical device within the anatomy of a patient. Guidewires
of invention advantageously reduces the likelihood that the
guidewire will fall out of the sterile field during a medical
procedure and become contaminated, requiring replacement. Methods
for making the guidewire also are disclosed.
Inventors: |
Rost; Michael C. (Souix Falls,
SD), Gabrielson; Daniel L. (Maple Grove, MN) |
Assignee: |
Lake Region Manufacturing, Inc.
(Chaska, MN)
|
Family
ID: |
25504387 |
Appl.
No.: |
08/961,366 |
Filed: |
October 30, 1997 |
Current U.S.
Class: |
600/585; 604/523;
604/526; 604/96.01 |
Current CPC
Class: |
A61M
25/09 (20130101); B21F 45/008 (20130101); A61M
2025/09083 (20130101); A61M 2025/09108 (20130101) |
Current International
Class: |
A61B
5/103 (20060101); A61M 27/00 (20060101); A61M
25/01 (20060101); B21F 45/06 (20060101); B21F
45/00 (20060101); B21F 3/02 (20060101); B21F
3/00 (20060101); A61M 027/00 () |
Field of
Search: |
;600/585,933,434
;604/95,96,280,281,282 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: O'Connor; Cary
Assistant Examiner: Wingood; Pamela
Attorney, Agent or Firm: Michael Best & Friedrich LLP
Frenchick, Esq.; Grady J.
Claims
What is claimed is:
1. An elongate, guidewire comprising a guidewire body having
coupled distal, medial and proximal segments, wherein at least a
substantial portion of at least one of said segments of the
guidewire has a substantially permanent disposition to assume a
coiled configuration whereby said segment has neither a time nor
temperature dependent tendency to return to a non-coiled
configuration.
2. A guidewire according to claim 1 wherein the segment having the
disposition to assume a coiled configuration is the medial
segment.
3. A guidewire according to claim 2 wherein substantially the
entire medial segment has a disposition to assume a coiled
configuration.
4. A guidewire according to claim 1 wherein the guidewire comprises
a wire core and a coil wire.
5. A guidewire according to claim 4 wherein the wire core comprises
stainless steel and the coil wire comprises an alloy of
platinum.
6. A guidewire according to claim 1 wherein at least a substantial
portion of the distal segment has a diameter which is less than
that of the medial segment.
7. A guidewire according to claim 1 wherein the guidewire comprises
a polymeric material.
8. A guidewire according to claim 1 wherein the guidewire comprises
a core wire having distal and proximal ends, a coil wire having
distal and proximal ends, and a safety wire, the proximal ends of
the core wire and coil wire being essentially coterminous and
attached to each other, the core wire terminating short of the coil
wire distal end, and the safety wire is attached to the distal and
proximal ends of the coil wire.
9. An elongate, guidewire comprising a guidewire body having
coupled distal, medial and proximal segments, wherein at least a
substantial portion of at least one of said segments of the
guidewire has a substantially permanent disposition to assume a
coiled configuration and said guidewire body comprises medical
grade stainless steel whereby said segment has neither a time nor
temperature dependent tendency to return to a non-coiled
configuration.
10. A guidewire according to claim 9, wherein the segment having
the disposition to assume a coiled configuration is the medial
segment.
11. A guidewire according to claim 9, wherein substantially the
entire
medial segment has a disposition to assume a coiled
configuration.
12. A guidewire according to claim 9, wherein the guidewire
comprises a wire core and a coil wire.
13. A guidewire according to claim 9, wherein the wire core
comprises stainless steel and the coil wire comprises an alloy of
platinum.
14. A guidewire according to claim 9, wherein at least a
substantial portion of the guidewire body distal segment has a
diameter which is less than that of the guidewire body medial
segment.
15. A guidewire according to claim 9, wherein the guidewire
comprises a core wire having a distal and proximal end, a coil wire
having a distal and proximal end, the proximal ends of the core
wire and coils wire being essentially coterminous and attached to
each other, the core wire terminating short of the coil wire distal
end, and a safety wire attached to the distal and proximal ends of
the coil wire.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
BACKGROUND OF THE INVENTION
This invention relates to the field of guidewires or wire guides
used for diagnostic, interventional, or therapeutic medical
procedures which define and are carried out within a sterile field.
More specifically, this invention relates to guidewires which are
conveniently useable within the spatial limits of a sterile field.
Guidewires of this invention also significantly reduce the
likelihood that they will become contaminated by physical
displacement from the sterile field or inadvertent contact with a
non-sterile surface.
Guidewires are used in various medical procedures to gain vascular
or non-vascular access to anatomical locations. The guidewire is
initially introduced into the anatomy of a patient by means of a
needle or other access device which in many procedures pierces the
patient's skin. The guidewire is then advanced to a chosen or
targeted anatomical location to provide a means of tracking
guidance and support for other diagnostic, interventional, or
therapeutic medical devices having lumens which can follow or track
over a guidewire. Once such other medical devices reach their
desired anatomical location, the guidewire is or can be withdrawn.
The physician then proceeds with the protocol of the procedure. A
specific but non-limiting example of the above is the placement of
a multi-lumen catheter into the internal jugular vein for
intraveneous delivery of medications. The physician achieves venous
access with a percutaneous introducer needle which penetrates the
surrounding tissue and vessel wall
as it enters the vessel lumen. The guidewire is inserted through
the introducer needle and advanced to the internal jugular vein.
The needle is withdrawn over the guidewire and placed on the
sterile field, i.e., the sterile area surrounding and adjacent to
the site of the medical procedure. A dilating sheath is inserted
over the guidewire and advanced through the skin to enlarge the
percutaneous opening. The dilating sheath is withdrawn over the
guidewire and placed in the sterile field. The multi-lumen catheter
is then slid over the guidewire by means of one of its lumens and
advanced to the desired location. Once the catheter reaches the
desired position within the vessel, the guidewire is withdrawn and
placed on the sterile field for possible future use.
Depending upon the nature and complexity of the procedure, the
physician may need or may choose to reinsert or use a number of
additional other diagnostic, interventional, or therapeutic devices
during the procedure. For example, fluoroscopic imaging may
disclose the catheter to be incorrectly positioned. In that
instance, the physician may choose to reinsert the guidewire to
provide support to the catheter as the catheter is withdrawn or
advanced to the correct position. Reinsertion of such other medical
devices will necessitate reinsertion of the guidewire into the
vasculature or to some other desired anatomical site. Numerous
other medical procedures requiring guidewire reinsertion will be
known to one skilled in this art. Thus, the guidewire must be
readily available for use and must maintain its sterility
throughout what may be a lengthy procedure.
The devices utilized during a procedure (including the guidewire),
are laid out on a sterile field to be readily accessible to the
physician throughout the procedure. The sterile field may include a
tray, a draped table, or a draped portion of the patient's body.
Therefore, the sterile field may be limited in space and sometimes
may not be level, but rather, uneven or tilted. For example, as a
preventative measure for reducing the likelihood of introducing an
air embolism during a central venous access procedure, the patient
table is commonly tilted with the patient's head angled downward
toward the floor.
As presently commercially available, a guidewire's unpackaged shape
is similar to a linear spring ranging in length from 30 centimeters
to 300 centimeters or more. The guidewire is usually packaged in a
circular carrier known as a dispenser, which has been discussed in
numerous United States patents including U.S. Pat. Nos. 5,443,081
and 5,279,573 both issued to James J. Klosterman. Once removed from
the dispenser, the guidewire returns to its straight, substantially
linear form. Because of the linear form and circular cross section
of the guidewire, it may inadvertently become displaced from the
sterile field by rolling or falling off. Additionally, its tendency
to be linear may result in contact with a non-sterile surface
outside of the limited sterile field such as a portion of the
patient's body, or a portion of the physician's body or a
contaminated object. In those instances where the guidewire is
displaced from the sterile field and has become contaminated, it is
necessary for the guidewire to be replaced with a second, sterile
guidewire. Replacement of the guidewire because of loss of
sterility is disruptive, inefficiently time consuming, and
increases the cost of the procedure.
At least two approaches have been taken to reduce the likelihood
that a guidewire will become contaminated by inadvertent contact or
displacement from the sterile field. One approach is to reinsert
the guidewire into its sterile dispenser, mentioned above, as it is
partially or wholly withdrawn from the patient. While this approach
is effective in protecting the wire from contamination, re-loading
the guidewire into the dispenser and removing it therefrom for
reuse requires additional time and may not be practical during a
medical procedure.
A second approach of which the assignee of this application has
become aware is to manufacture the guidewire from a material having
a temperature dependent configuration , i.e., the configuration the
guidewire tends to assume, is determined by the temperature to
which the guidewire is exposed. Materials useable in this approach
can be processed to have a tendency to coil at room temperature
(e.g., 25.degree. C.) outside the body and to uncoil, i.e., to
become substantially linear, at body temperature (e.g., 37.degree.
C.) e.g., when it is reinserted into the body. As is well known in
the medical device art, specific nickel titanium alloys (e.g.,
nitinol) can be processed to exhibit this behavior. This second
approach has the significant drawback that the materials which are
suitable for manufacturing guidewires and which exhibit a
temperature dependent configuration are generally difficult to
fabricate into conventional guidewires because they are resistant
to conventional welding and brazing processes. Additionally, such
temperature dependent materials tend to be more expensive than
conventional metals such as medical grade stainless steel.
The present invention provides the physician with a means of
efficiently, conveniently and cost effectively reducing the risk of
inadvertent contamination of the guidewire during a medical
procedure use and handling, without re-loading the guidewire into
its dispenser or utilization of materials which exhibit
temperature-dependent memory.
BRIEF SUMMARY OF THE INVENTION
Briefly, in one aspect, the present invention is an elongate
guidewire comprising a guidewire body having coupled or connected
distal, medial and proximal segments. At least a substantial part
of at least one of the distal, medial or proximal guidewire
segments has a substantially permanent disposition or
pre-disposition to assume the configuration or shape of a helical
coil. Put otherwise, a guidewire of this invention self-coils to a
coiled, usually circular, configuration or arrangement. In a
preferred embodiment, substantially the entire guidewire body has a
substantially permanent predisposition to coil. In yet a further
preferred embodiment, the guidewire comprises metal which does not
exhibit temperature dependent memory, especially including
substantially conventional ferric metal such as medical grade
stainless steel (e.g., 304 stainless steel).
The term "guidewire" as used herein is to be broadly construed to
mean essentially any wire-like structure of dimension and length
which is intended to assist in the placement of a catheter or other
medical device at a site of medical interest. (Percutaneous
procedures in which placement of a catheter or other device through
the skin is contemplated, are a preferred category of medical
procedures in which guidewire are used.) Guidewires herein is
intended to include but is not limited to what is usually referred
to as a guidewire, a main wire, introducer guidewires, diagnostic,
therapeutic or interventional guidewires, wire guides, and spring
guidewires, but also includes exchange guidewires and extension
wires. Dimensions of guidewires to which the present invention
applies falls in the range of about 0.010 in. to about 0.065 in. in
diameter and about 30 cm to about 300 cm (or more) in length.
Without limiting the generality of the foregoing, peripheral,
cerebral (including neuro-interventional), cardiovascular
(including coronary) guidewires or wire guides are within the
contemplation of this definition. Guidewires of the present
invention may include structure (e.g., on their extreme proximal
segment) which permits them to be extended during a procedure by
connection to a second (extension wire) guidewire. Guidewires of
this invention may be coated or treated with various polymers or
other compounds to change their handling or performance
characteristics such as to increase lubricity, or to reduce
thrombogenicity. Guidewires of the invention may also be
uncoated.
Guidewires of the present invention, are required to have in at
least some substantial portion of the body thereof a substantially
"permanent" disposition or predisposition to coil. By this
terminology it is intended that the guidewire, especially a
substantial portion thereof, will have a substantially permanent,
non-transitory, i.e., neither time nor temperature dependent,
tendency or predisposition to maintain itself, or to return to (if
it has been uncoiled) a coiled, usually circular, configuration. A
substantially permanent predisposition to coil should not be
narrowly construed to mean predisposition to return to precisely
the same coiled configuration as was assumed before uncoiling.
Coiling and uncoiling a guidewire of this invention, e.g., in the
performance of multiple catheter exchanges, may change the precise
coiled configuration to which the guidewire returns when it
recoils. Such minor changes in the coil configuration (especially
those associated with the use of guidewire of this invention) are
intended to be within the definition of a substantially permanent
predisposition to coil. As is described in greater detail below, a
permanent predisposition to coil can be imparted to relatively
conventional metals such as stainless steel. To obtain various
other performance characteristics, e.g., radiopacity, guidewire
components may be fabricated from alloys of platinum, gold,
tantalum, nickel, titanium, or cobalt. Guidewires of this invention
also may be fabricated from nonmetallic, polymer materials,
assuming such materials display a permanent disposition or
predisposition to assume a coiled configuration in accordance with
this invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be discussed in detail, the
understanding of which will be enhanced by reference to the
attached drawings wherein like numerals are used to refer to like
features and wherein:
FIGS. 1A and 1B are perspective, schematic views of guidewires of
the present invention;
FIG. 2 is a detailed, partially sectional view of one embodiment of
the present invention;
FIG. 3 is an exploded view of an assembly step in a method of this
invention.
FIG. 4 is a detailed, partially sectional view of a second
embodiment of this invention.
FIGS. 5 and 6 illustrate coiled guidewire carriers.
FIGS. 7-11 are schematic, perspective illustrations of tooling used
to impart a permanent predisposition to coil to guidewires of the
present invention.
FIGS. 12A-12D illustrate the finger-straightenable optional feature
of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The invention will now be described with reference to the drawings
noted above and the attached claims. The description of the present
invention will focus upon its application to medical guidewires as
that term is ordinarily understood in this art. However, the
invention is not intended to be limited to medical guidewires as
discussed herein and should be construed in accordance with the
above definitions.
FIGS. 1A and 1B are schematic depictions of guidewires 10, 10' of
the present invention shown in their coiled configuration.
Guidewires 10, 10' comprise a guidewire body having a connected or
coupled proximal segment 12, 12', a distal segment 14, 14', and a
permanently coiled medial segment 16, 16'. The terminology
proximal, medial, and distal, as it is used with reference to
guidewire structure, will be well understood by one skilled in this
art to mean structures of the wire as determined from the user's
perspective. More specifically, the distal segment of a wire of
this invention generally means that portion of the guidewire which
first enters a patient's anatomy when the device is utilized. The
distal segment of any particular guidewire tends to be more
flexible than the rest of the guidewire. This distal segment of a
guidewire also may be bent to have a "J" configuration as viewed
from the side. The medial segment of the guidewire is generally any
portion of the wire between the distal segment and the proximal
segment. The proximal segment of the wire is generally that portion
of the wire where much of the manual manipulation of the guidewire
occurs and which does not usually enter the patient's anatomy
during a medical procedure. In any particularly instance,
designation of a guidewire length into distal, medial, and proximal
segments is not particularly critical as the present invention may
be applied to any, all, or a combination of those guidewire body
segments. Generally speaking, the medial segment of a guidewire of
this invention will comprise a majority of the length of the
guidewire body and will be imparted with a predisposition to assume
a coiled configuration in accordiance with this invention. In this
general practice of the present invention, a greater percentage of
the guidewire body is coiled, thereby imparting control and the
advantageous handling characteristics of this invention to more of
the guidewire body.
In the embodiments of FIGS. 1A and 1B, the distal-most portion of
the guidewire has a "J" configuration or distal tip 18, 18' which
tends to make the extreme distal end of distal segment 14, 14' of
the wire atraumatic to the patient's vessels, tissue and other body
structures with which it comes in contact during use. While a "J"
distal guidewire tip configuration is illustrated with respect to
this invention, a straight distal tip, or merely a bent distal tip
are equally within its scope. As is shown in FIG. 1A, the proximal
segment 12 of wire 10 is substantially straight having no
disposition to coil. Proximal coil segment 12', as shown in FIG. 1B
has a slightly curved configuration, albeit with a radius of
curvature larger than that of medial segment 16'. Proximal segments
12, 12' may be designed to have various configurations, including
bent, slightly to extremely curved or circular, depending upon the
intended use for the wire. Proximal segment 12, 12' and distal
segment 14, 14' may be imparted with a tendency to assume a
configuration in which their respective radii of curvature are
substantially the same as that of medial segment 16, 16'. In that
embodiment, the only deviation from the curved configuration
throughout the entire length of guidewires 10 or 10' would be the
extreme distal tip 18, 18'. Generally speaking, at least some part
of one or both distal segments 14, 14' and proximal segments 12,
12' will be substantially straight (or will be made to be
straightened during the procedure as is described below) so as to
make easier the advancement of guidewire 10, 10' through an
introducer needle or other entry device. The straight length of
segments 12, 12' and 14, 14' (which may be the same or different)
generally ranges from about 5 cm to about 30 cm.
Medial segment 16, 16' of guidewires 10, 10' is shown to be curved,
or more precisely circular in FIGS. 1A and 1B. Elliptical,
flattened elliptical, or various other permanent configurations may
be imparted to the wire in accordance with this invention. One
skilled in this art will appreciate that essentially any permanent
configuration which tends to contain or manage all or substantially
all of the sometimes cumbersome length of the guidewire body to
make it more controllable during a medical procedure (and also to
reduce the likelihood that the device will leave the sterile field)
is within the contemplation of this invention. It is also to be
understood that guidewire proximal segment 12, 12' and distal
segment 14, 14' are generally much shorter in length that medial
segment 16. For example, the distal and proximal segments 12, 12'
and 14, 14', respectively, of a guidewire of this invention may
fall in the range of 5 cm to 30 cm while the length of the entire
guidewire may fall in the range of 30 cm to 300 cm or more. Thus,
while medial segment 16, 16' is shown to comprise a single coil in
FIGS. 1A and 1B, it is to be understood that medial segment 16, 16'
may comprise a plurality of coils depending upon overall guidewire
length. Generally speaking, whether medial segment 16, 16'
comprises a single permanent coil, or a plurality of permanent
coils, the preferred coil diameter ("D" in FIGS. 1A and 1B) falls
in the range of about 21/2 inches (10 cm) to about 10 inches (25
cm). Using a predispositioned coil diameter ("D") in the range
discussed above in conjunction with the indicated ranges for
guidewire length and cross-sectional diameter, the guidewire will
have a permanent disposition to coil when withdrawn from the
patient without having an excessive tendency to do so, i.e., so as
to cause injury while in the patient. In essence, the patient's
anatomical structure will overcome the tendency of the guidewire to
self-coil, permitting the guidewire to be inserted and withdrawn
without unwanted deflection. The guidewire then returns to its
coiled configuration as it is withdrawn from the constraints of
the
patient's anatomical structure.
It is to be understood that the preferred practice of the present
invention is to impart a substantially permanent coil
predisposition or self-coiling disposition to the medial segment of
a guidewire. Generally speaking, this means that all or
substantially all of the medial segment of the wire will be
imparted with a predisposition to assume a curved structure or
substantially circular configuration. Depending upon the intended
application, the predisposition to curve may be imparted to the
medial segment, either of the proximal and distal segments, both of
the proximal and distal segments or all of the distal, medial, or
proximal guidewire segments.
At least two processes have been identified for permanently
imparting such predisposition to the various guidewire segments,
i.e., cold forming and hot forming. The particular process chosen
may, in part, be determined by the structural configuration of the
guidewire. Other processes may occur to one skilled in this art. A
brief description of a preferred guidewire of this invention may
assist in the comprehension of the fabrication processes described
below.
The preferred guidewire structure for application of the present
invention is an assembly of a coil component and a core component
as is shown in FIG. 2. In FIG. 2, there is shown a guidewire 30
which comprises a core component such as core wire 32 (sometimes
referred to as a mandril in prior art patents) and a coil component
such as coil wire 34. Coil wire 34 is shown partially cut-away and
in section to permit discussion of the guidewire interior
structure. Guidewire 30 has a proximal segment 31, and a distal
segment 33. Guidewire 30 of FIG. 2 is shown in segments to permit
the various structural features to be discussed. It is to be
understood that a medial segment having a substantially permanent
predisposition to assume a curved or coiled configuration would be
located between proximal segment 31 and distal segment 33. In FIG.
2 coil wire 34 is disposed around essentially the entire length of
core wire 32. Coil wire 34 is closely wound meaning that individual
coils 36, 38 are in contact with each other. Coil wire 34 could be
space wound, meaning that individual coils thereof would not be in
contact each other and would have air space therebetween. Coil wire
34 also could be partially space wound and partially closely wound
(shown in FIG. 3). Coil wire 34 is attached to core wire 32 at its
most distal and proximal ends by distal weld 40 and proximal weld
42. Welds 40 and 42 are rounded or atraumatic so as to reduce
possible damage to the structure of any cooperating device or any
tissue with which they may come into contact. Braze, solder, or
adhesives are other means for attaching the coil and core
components.
FIG. 3 illustrates the individual coil wire 34 and core wire 32
components prior to assembly. It is to be noted that the term wire
as used in this context includes a linear and coiled wire segments.
Multifilar guidewire structures comprising a plurality of wound
coil structures, are also within this definition. Distal segment 33
of core wire 32 has a first tapered section 44 and is coupled to a
reduced diameter distal portion 46. Tapered section 44 and reduced
diameter portion 46 provide enhanced flexibility to the distal
segment of the guidewire. Such structures may be used on either or
both the distal and proximal ends of a guidewire, especially is the
guidewire is designed so that either end of the guidewire may be
inserted into the patient's anatomy. Wire core 32 may also include
a flattened extreme distal section (or an extreme proximal section)
on either or both of its ends to impart flexibility thereto. For
illustrative purposes only (i.e., the assembled structure of the
FIGs. do not have a partially space wound coil) coil wire 34 is
shown to have a tightly wound portion 35 and a space wound portion
37.
FIG. 4 shows a further embodiment of a guidewire configuration 59
with which the present invention may be used. As with FIG. 3, the
coiled medial segment has been deleted but should be understood to
be implicitly present. In FIG. 4, there is shown a core wire 60,
and a wire coil 62 in which core wire 60 terminates short of the
distal end 40 of the wire coil at distal ball weld 64. Wire core 60
has distal ball weld 64 which reduces the likelihood that core wire
60 will project from between the coils of coil wire 62. Running the
entire length of guidewire 59 is safety wire 66. Safety wire 66 is
attached to wire coil 62 at distal weld 40 and proximal weld 42.
This embodiment of the invention would be used where an especially
flexible or "floppy" distal tip guidewire is required. As in the
embodiment of FIG. 2, core wire 60 has a first tapered segment 70
leading to a reduced diameter segment 72.
FIGS. 5 and 6, illustrate further embodiments of the present
invention in which guidewires within its scope are contained within
single 20 and multiple coil 22 guidewire carriers. Also shown in
FIGS. 5 and 6 is the utilization of a "J" straightener 24 which, in
accordance with known practice, temporarily straightens the distal
"J" tip to permit the tip to be inserted into the vasculature,
e.g., through an introducer wire. See, e.g., U.S. Pat. No.
4,650,472. While the present invention has been discussed in
conjunction with the utilization of guidewire carriers, one
advantage of this invention is that it provides the option to use a
guidewire without the need for a guidewire carrier. The permanent
predisposition of a guidewire to coil, in accordance with this
invention, provides many of the transportation, handling, and
packaging functions of a guidewire carrier and, depending upon user
preference, may be substituted therefor. In this manner the expense
of the guidewire carrier itself and of its environmentally
acceptable disposal may be reduced or eliminated.
In a cold rolling process, the segment of the guidewire into which
a permanent coiling predisposition is to be imparted is passed
between a series of rollers at room temperature, after the wire
core and coil wire have been attached to each other, e.g., at welds
40 and 42. In one version of a cold rolling process a series of 4
rollers as is shown in FIGS. 7-11 is used.
In FIGS. 7-11 (specifically FIG. 7) there is shown a primary bend
pin or roller 50, control rollers 52 and 54, and a bend backroller
or sizing roller 56. Roller direction is shown by arrows 55. In
each of rollers 50 and 56 there is a groove or channel 57 which is
sized and aligned with the other rollers to receive a guidewire
(not shown). It is preferred that at least one of bend roller 50,
control rollers 52 and 54 or bend backroller 56 have a
guidewire-sized channel or groove to retain the guidewire between
the rollers in the bending process. A substantially permanent
predisposition to assume a coiled configuration is imparted to a
guidewire (in this example, the medial segment) in the following
manner.
Referring to the top view of FIG. 8, the medial segment of
guidewire 30 is placed between control rollers 52, 54 and bend
roller 50 in channel 57 (not shown). Control rollers 52, 54 then
are moved toward bend roller 50 in the direction of arrows 51 (FIG.
9) to start the bending process. Control rollers 52, 54 are rotated
clockwise with main bend roller 50 holding guidewire 30
therebetween and rotating counter-clockwise to impart an initial
bend to the guidewire (FIG. 10). Generally speaking, guidewire 30
will be overbent during this initial step to ensure that the
guidewire, will return to the desired shape or degree of curvature
and after procedural use and handling. Sizing or bendback roller 56
may then be moved into position in the direction shown by arrows 53
as is shown in FIGS. 10 and 11 to modify the bend and therefor the
extent of the coiling predisposition imparted to the guidewire. One
skilled in the art of bending wire will appreciate that the
relative locations and relative diameters of rollers 50,52, and 54
may be changed to impart particular curvilinear predispositions
(i.e., coil diameters or coil memory) to produce a self-coiling
guidewire structure in accordance with this invention. Adjustment
of the roller diameters and of the number of times the guidewire is
rolled therebetween also will determine the aggressiveness or
resistance to uncoiling the guidewire exhibits.
In a heat forming process, wire core 32 is heated to a temperature
in the range of about 500.degree. F. to about 1200.degree. F. for a
minimum time period of from about 15 minutes while it is maintained
in a looped or coiled configuration. Heating the wire core to a
temperature in the indicated range while maintaining it in a coiled
configuration tends to relieve any stresses in the metal and, upon
cooling to room temperature, produces a permanently coiled wire
core in accordance with this invention. Thereafter, the coiled wire
core is attached to the coil wire by inserting the wire core into
the coiled wire and joining the distal and proximal ends of wire
core and the coil wire. The coil wire, being substantially more
flexible than the wire core tends to assume the same coiled
configuration as the wire core. In this later, heat forming
process, "J" guidewire tip configurations are generally imparted to
the distal end of the guidewire between attachment (e.g., by
welding) of the distal and proximal ends of the guidewire
structure. This permits the length relationship between the coil
and the core to be more precise.
The embodiment of the present invention shown in FIGS. 2 and 4 have
an optional feature, in that the "J" tip is finger-straightenable.
Finger-straightenability is imparted to the "J" distal tip by
manufacturing coil 62 from a wire diameter which is typically
0.001" smaller than convention coil wire size. Additionally, safety
wire 66 (FIG. 4) or core wire 60 (FIG. 4) are downsized from
conventional designs (e.g., by a reduction in cross-sectional
thickness of at least 15%) to create less resistance to opening of
the J-shaped tip. Reference is now made to FIGS. 12A-12D in which
finger straightenability is illustrated.
FIG. 12A illustrates a guidewire 30 such as that of FIG. 2, above,
held between the gloved thumb 80 and forefinger 82 of the guidewire
user. Arrow 84 indicates that the guidewire 30 is gripped
approximately 5-6 cm from its distal "J" tip 18. In FIG. 12B,
triangles 86 indicate that the guidewire is held securely between
the thumb 80 and forefinger 82 while wrapping fingers 88 around
guidewire 30 pressing guidewire 30 against the user's palm 90. As
is shown in FIG. 12C, forward pressure (indicated by arrow 92) is
applied with the thumb 80 while simultaneously pulling downward
with the remaining fingers 82,86 (indicated by arrow 94) until the
guidewire "J" distal tip 18 gently straightens (as is shown by
arrow 96 and the phantom "J" tip, 18'.) Alternatively, as is shown
in FIG. 12D., forward pressure is applied by both the thumb 80 and
forefinger 82 (in the direction of arrows 100) while holding
guidewire 30 with the remaining fingers 88. In like manner, the
guidewire "J" distal tip 18', 18 is straightened. After
finger-straightening the "J" distal tip as illustrated, the
guidewire than can easily be introduced into an introducer needle,
a cannula, or a catheter or other structure without the assistance
of a separate "J" straightening device.
Materials of which the wire core and coil wire may be made are
substantially conventional. Stainless steel, e.g., 304 stainless
steel, nickel and nickel alloys, e.g., MP-35N, cobalt alloys, and
various other ferrous metals commonly used in guidewire fabrication
may be used. Radiopaque alloys such as platinum and titanium may be
used to fabricate, in whole or in part, either or both of the wire
core and the coil wire or various other structural components.
Etches may be applied to the guidewire body. As is noted above,
multifilar construction using any of the above materials is also
within the contemplation of the present invention.
The above-described preferred guidewire structure is used
substantially without a coating of any sort. Obviously, various
coatings could be imparted to the wire core, the coil wire, or both
without departing from the scope of the present invention. PTFE and
hydrophilic coatings are commonly used to impart desirable handling
characteristics to a guidewire. Such coatings are within the scope
of the present invention.
The present invention has been particularly described with respect
to the utilization of guidewires, primarily to obtain percutaneous
vascular access. Non-vascular access applications are also within
the scope of the present invention. For example, a device of the
present invention may be used to assist in the performance of
percutaneous nephrostomy, biliary and abscess drainage and other
gastrointestinal and genitourinary procedures.
In one application, then, a guidewire of this invention is removed
from its guidewire carrier, examples of which are shown in FIGS. 5
and 6 by withdrawing it therefrom. Upon removal, the guidewire
returns to its substantially permanently coiled disposition. The
user then inserts the extreme distal end, e.g., the "J" tip, as
described above into the chosen percutaneous access device after it
is straightened by means of a "J" straightener or by utilization of
finger straightenability. The guidewire then is steered to the
previously chosen site of medical interest by uncoiling it while
inserting it into the patient. Using the coil diameter
above-discussed (i.d., the "D" dimensions) in conjunction with the
indicated guidewire length and diameters, the guidewire will not
have an excessive tendency to coil while in the patient. In
essence, the user's hands and the patient's anatomical structure
overcome the tendency of the guidewire to self-coil and permit the
guidewire to be inserted. When the guidewire is withdrawn from the
patient, e.g., to exchange catheters, the guidewire returns to its
coiled configuration as it is withdrawn.
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